The invention relates to systems for recording and reproducing digital audio signals on and from a re-recordable record carrier. Such systems comprise a recording apparatus for recording a digital audio signal in a track on the record carrier and a reproducing apparatus for reproducing a digital audio signal from the track of the record carrier substantially corresponding to the digital audio signal recorded therein.
The recording apparatus comprises: (a) an input terminal for receiving a digital audio signal; (b) a first conversion unit for converting the digital audio signal in a data reduction step into a second digital signal comprising synchronization information and audio information, i.e., bit allocation information, scale factor information and samples of sub-band signals derived from the digital audio signal, included in subsequent frames of the second digital signal; (c) a second conversion unit for converting the second digital signal into a third digital signal which is error correction encoded, and (d) a write unit for writing the third digital signal in a track on the record carrier.
The reproducing apparatus comprises: (a) a read unit for reading a replicated third digital signal substantially corresponding to the third digital signal from the track on the record carrier; (b) a first deconversion unit for (i) correcting errors in the replicated third digital signal (ii) generating an error-flag if it is not capable of correcting an error, and (iii) reconverting the replicated third digital signal into a replicated second digital signal which substantially corresponds to the second digital signal; (c) a second deconversion unit for converting the replicated second digital signal into a replica of the digital audio signal; (d) a concealment unit for concealing uncorrectable errors in the replica of the digital audio signal in response to error flags generated by the first deconversion unit; and (e) an output terminal for supplying the replica of the digital audio signal. The invention also relates to recording apparatus and methods and reproducing apparatus for use in the systems. In addition, the invention relates to re-recordable record carriers obtained with the recording methods.
A system in accordance with the systems of the opening paragraphs is described in Dutch Patent Application No. 91.00.285, which corresponds to U.S. patent application No. 07/827,789, filed Jan. 1, 1992. That patent application describes a system including a recording apparatus and a reproducing apparatus of the DCC type, which enable audio signals in digital form to be recorded and reproduced on and from a magnetic record carrier incorporated in a compact cassette like housing. The audio signal reproduced has substantially a CD quality.